Multi-Harmonic Permanent Magnet Motor Rotor Pole Width Design
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Solution Overview
Problem
Existing permanent magnet motors have limited torque density and fault tolerance due to their design, which generates only one working harmonic, leading to unstable output and torque ripple, failing to meet the demands of emerging industries like electric vehicles and industrial robots.
Innovation Solution
A rotor design with alternately distributed N and S poles of varying widths, allowing for the generation of multiple harmonic magnetic fields that interact with armature windings to produce multi-part torques, enhancing torque density and fault tolerance by decoupling harmonic frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a permanent magnet motor uses only one working harmonic for torque generation, then the motor structure is simple, but the torque density is limited and output is unstable
Solution Approach 1:
The patent segments the single working harmonic into multiple working harmonics by designing specific rotor pole structures. The rotor includes multiple pole pairs with different pole numbers (e.g., 12 poles and 10 poles), each generating different harmonic components. This segmentation allows the motor to utilize multiple harmonic fields simultaneously, improving output stability and torque density while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent applies local quality by creating non-uniform pole width distributions on the rotor. Different pole pairs have different pole arc coefficients (e.g., β1 ≠ β2), which locally modifies the magnetic field distribution. This local variation enables the generation of multiple harmonic components with different amplitudes, allowing selective utilization of multiple working harmonics to improve torque characteristics.
2Device complexity
If a permanent magnet motor uses only one working harmonic, then the control is simple, but the torque density is limited
Solution Approach 1:
The patent introduces dynamic control by independently controlling the currents corresponding to different working harmonics. The control system adjusts the amplitude and phase of multiple current components (i1, i2, ...) corresponding to different pole pairs dynamically. This dynamic control enables flexible optimization of torque density while keeping the control structure manageable through modular current control strategies.
Solution Approach 2:
The patent uses composite magnetic field structures by combining multiple harmonic fields with different pole numbers. The rotor employs composite pole configurations (e.g., combining 12-pole and 10-pole structures) that generate multiple harmonic components. This composite approach allows the motor to achieve higher torque density by superimposing torques from multiple harmonics, while the control system handles the complexity through coordinated current regulation.
3Ease of manufacture
If all pole pairs have the same width, then the manufacturing is simple, but multiple harmonic fields cannot be effectively generated
Solution Approach 1:
The patent implements local quality by designing different pole arc coefficients for different pole pairs. Specifically, the rotor has pole pairs with varying pole widths (e.g., first pole pair with coefficient β1, second pole pair with coefficient β2, where β1 ≠ β2). This local variation in pole geometry is achieved through precision molding or machining techniques, balancing manufacturing feasibility with the need to generate multiple harmonic fields with distinct characteristics.
Solution Approach 2:
The patent changes geometric parameters of the rotor poles to enable multiple harmonic generation. By adjusting the pole arc coefficients and pole widths of different pole pairs, the magnetic field distribution is modified to produce multiple working harmonics. These parameter changes are incorporated into the rotor design specifications and manufacturing processes, achieving the desired harmonic composition while maintaining manufacturability through standard engineering tolerances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design significantly increases torque density and improves fault tolerance by utilizing multiple harmonic fields as working harmonics, effectively increasing output torque and enhancing motor performance.
Implementation Method 1
to generate a stable torque by the interaction of the magnetic fields of the stator and the rotor
Implementation Method 2
the number of pole pairs refers to the number of peaks or troughs of sinusoidally distributed flux density waveform
Implementation Method 3
an electromagnetic device that realizes the conversion of electromechanical energy or signals
Data Source
AI summary
The present invention discloses a stator, a rotor and a multi-working-harmonic permanent magnet motor using the above rotor and the stator, wherein the N poles and the S poles are alternately distributed in a circumference direction of the rotor core or the stator core; any N pole comprises at least one N-pole permanent magnet; any S pole comprises at least one S-pole permanent magnet; and at least two adjacent N pole and S pole has different widths. According to the invention, through the arrangement of magnetic poles with different widths on a rotor or a stator, it is possible to generate magnetic fields containing a plurality of harmonic magnetic fields with high amplitudes so that the harmonic magnetic fields can interact with the magnetic fields generated by the armature windings of the permanent motor to realize the superposition of multi-part torques, thereby further enhancing the outputted torque of the motor. In addition, with the invention, the harmonic permanent fields can be completely decoupled on the frequency, thereby significantly improving the fault tolerance performance of the motor, and as a dual-mechanical-port motor, the motor of the invention can be applied to electric vehicles and other relevant variable transmission field.